Pour the melted butter into a 9 x 12-inch oven-safe dish. Sprinkle the brown sugar and 1 teaspoon of the cinnamon evenly over top. Arrange the bread slices in the pan so they are overlapping.
In a medium bowl, beat together the eggs, milk and vanilla with a whisk until smooth. Pour the mixture over the bread and cover with plastic wrap. Refrigerate overnight.
Preheat the oven to 350˚F.
Transfer the dish to the preheated oven and bake for 25 minutes. Meanwhile, in a small bowl, mix together the sugar and remaining ½ teaspoon cinnamon. Remove the dish from the oven and sprinkle the cinnamon-sugar mixture evenly over top. Return the dish to the oven and increase the temperature to 450˚F. Bake until the toast is golden and crisp on top, about 10 more minutes.
Many people use soft sandwich bread for their French toast. I love using a crusty loaf of bread. It creates a sweet, crunchy outside to this French toast bake which is lovely.
For everything you could possibly want to know about preparing French toast, check out this great post by Olivia Rose at My King Cook.